Have you ever cheated on a significant other.
No, never!
Should you/did you tell them that you did. Exceptions? Can't answer that b/c I've never been in that position.
Would you want to know? Why?
Yes, I would want to know so I could find out the reasons behind it.
What would you do if you found it they did that to you? Stay together etc?
I stayed together with one boyfriend after finding out he had cheated because we had been together for so long and I really wanted to work things out. But we broke up a couple of months later because of trust issues. When another boyfriend (who was living with me at the time) cheated, I had the locks changed while he was at work.